INTERPLAY OF NUCLEAR MAGNETISM WITH ELECTRONIC MAGNETISM AND SUPERCONDUCTIVITY

The discovery of a nuclear ferromagnetic transition of In nuclei in Au In2 at T-c = 35 mu K has opened the possibility to study the interplay of a nuclear magnetically ordered state with other condensed matter p henomena in thermal equilibrium between nuclei and electrons. In this contribution we will discuss the mutual influence of nuclear ferromagn etism and type-I superconductivity in AuIn2 at T greater than or equal to 25 mu K. The two phenomena coexist, however, the critical field of superconductivity is decreased and the transition is broadened by the nuclear ferromagnetic transition. - For another favourable candidate for a nuclear magnetic transition, platinum, we have not yet observed a transition to a nuclear spin temperature of 0.3 mu K and an equilibr ium temperature of 1.5 mu K However, we use the nuclear magnetic heat capacity as well as the spin-lattice and spin-spin relaxation times of Pt to study the influence of Fe impurities in the ppm concentration r ange on the nuclear magnetic properties of the Pt host.